In November 2005, Teo also took on the role of Director of Human Resources at the Administration and Research Unit (ARU) of the National Trades Union Congress (NTUC).

After her election to Parliament in 2006, Teo also took on additional roles within the NTUC and the labour movement. She served as the Executive Secretary of the Singapore Industrial Services Employees' Union (2006-11). At the ARU, she served as the Alignment Director (Youth Development) and Alignment Director (Organisation Development) (2007-11), and as the Centric Director (Staff) (2008-11).[4] She also served as the NTUC's Assistant Secretary-General from 2007 to 2011.[5]

From 2009 to 2011, Teo also served as the Chief Executive Officer of Business China,[6][7] an organisation established to nurture an inclusive bilingual and bi-cultural group of Singaporeans through the use of Chinese language and to develop a cultural and economic bridge between China and the world.[6]

Teo entered Parliament at the 2006 general election as an MP for the Bishan-Toa Payoh Group Representation Constituency (GRC).

In Teo's maiden speech in Parliament, she called on the Government to "rethink the way we teach our children our history, and that we preserve the evidence of our past through art and architecture so that, as a people, we will never forget."[citation needed] She believed that if Singapore focuses her attention on the non-negotiables, namely national security, economic survival and education, is careful to avoid deepening the potential divides in the society - the “young” versus the “old”, “local” versus “foreign”, “haves” versus “have-nots”, and avoid the three attitudes that can lead to Singapore's downfall, Singapore will, indeed, be able to build a more inclusive society.[citation needed]

During her first term in Parliament, she served as the Chair of the Government Parliamentary Committee (GPC) for Education, and as a member of the GPC for Defence & Foreign Affairs.[8]

Following the 2011 general election, Teo was appointed a Minister of State at the Ministry of Finance and the Ministry of Transport on 18 May 2011, succeeding Ms Lim Hwee Hua. Teo was promoted to Senior Minister Of State at the Ministry of Finance and the Ministry of Transport on 1 September 2013.